Ackman has been pursuing an aggressive bet against the nutritional supplements maker, staking huge sums of money on his belief that the company's shares would fall. But the stock has roughly doubled this year alone.

On Monday Herbalife beat estimates for the 18th quarter running and raised estimates for the year.

Ackman, in a statement, said he had a number of questions for the company, among them the impact of price increases and the rate at which distributors were leaving the company.